Functionalization of single- and multi-walled carbon nanotubes (CNTs) has attracted increasing attention due to their outstanding structural, chemical, electrical, and thermal properties. Methods developed for functionalizing CNTs include the formation of non-covalent as well as covalent assemblies. Among these, the modification of CNTs with metal nanoparticles can provide unique properties leading to advanced catalytic systems, very sensitive electrochemical sensors, and highly efficient fuel cells. Up to now, only a few protocols have been devised for attaching metal particles onto CNTs; these have included chemical binding through DNA double-helix linkages, electrochemical deposition, electroless deposition with and without the aid of reducing agents, and physical/chemical deposition on CNTs with and without surface activation.
Quantum dots provide a functional platform for the creation of novel materials and devices that benefit from the unique physical properties arising from their quantum-confined nature and properties, which are intermediate between those of the molecular and bulk size scales. They have also formed the basis for new photovoltaic cells, light-emitting diodes, bio-sensors, and other hybrid materials prepared by directed- and self-assembly techniques. These semiconducting nanoparticles have photophysical properties that are superior to many organic-based materials, and the use of dendrimers as nanoreactors, stabilizers and templates for their preparation presents advantages, such as temperature and size control.